The present invention relates to a heater suitable for use with charging devices, and more particularly to method and apparatus for improving charge uniformity and minimizing AC coupling to heater lines on chargers.
Charged particles, or ions, can be generated in a number of different ways. Known techniques include the use of air gap breakdown, corona discharges and spark discharges. One specific method and apparatus for generating charged particles is discussed in U.S. Pat. No. 4,155,093 to Fotland et al. The method of generating ions in air as described in the ""093 patent includes applying an alternating potential between a first electrode that is substantially in contact with one side of a solid dielectric member and a second electrode substantially in contact with an opposite side of the solid dielectric member. The second electrode has an edge surface disposed opposite the first electrode to define an air region at the junction of the edge surface and the solid dielectric member. This induces ion producing electrical discharges in the air region between the dielectric member and the edge surface of the electrode. An ion extraction potential is applied between the second electrode and an additional electrode member to extract ions produced by the electrical discharges in the air region.
The device and method described in the ""093 patent is similar to the method and apparatus for a charging device known as a solid-state charger. The solid-state charger also extracts charges (ions and/or electrons) from a high-density plasma source. The source is created by electrical gas breakdown in a high frequency AC field between two conducting electrodes that are separated by an insulator. The potential of the electrode directly facing the photoreceptor determines the polarity and magnitude of charging current.
The solid-state charger often performs more efficiently at an elevated and uniform temperature. If the solid-state charger maintains some portions at warmer or cooler temperatures than other portions, the performance of the charger is diminished.
There is a need in the art for a method and apparatus for heating a charging unit to an appropriate temperature in a uniform manner. The present invention is directed toward further solutions to address this need.
In accordance with one example embodiment of the present invention, a heater for use in a charger includes a base. A first contact is disposed on the base and a second contact is also disposed on the base. A heating element couples the first contact and the second contact. The heating element is arranged such that an energy density of the heating element increases approximately exponentially from a first energy density at locations distal from the first and second contacts to a relatively higher second energy density at locations proximal to the first and second contacts.
The heater, according to one aspect of the present invention, mounts on a charger that is a solid-state charger.
The heating element, according to one embodiment of the present invention, is arranged on the charger in a generally elliptical pattern. Alternatively, the heater according to a second embodiment is arranged in a generally zigzag pattern. It should be noted that the exact pattern or profile of the heater element can vary, and is generally non-uniform.
According to further aspects of the present invention, the base is formed of a substrate having a first end and a second end. The first contact is disposed proximal to the first end of the base and the second contact is disposed proximal to the second end of the base.
In accordance with still further aspects of the present invention, the charger to which the heater mounts includes a substrate layer. An AC electrode layer couples with the substrate layer. A dielectric layer couples with the AC electrode layer. An aperture electrode layer further couples with the dielectric layer and is electrically insulated by the dielectric layer from the AC electrode layer.
The heater, according to further embodiments of the present invention, is disposed on an opposite side of the substrate layer from the AC electrode layer of the charger.
According to still another aspect of the present invention, a method of forming a heater for a charger is provided. The method includes providing a base. A first contact and a second contact are arranged on the base. The first contact is coupled with the second contact by a heating element in a manner such that an energy density of the heating element increases from a first energy density at locations along the heating element distal from the first and second contacts to a relatively higher second energy density proximal to the first and second contacts.
In accordance with still a further aspect of the present invention, a charger is provided that includes a substrate layer. An AC electrode layer couples with the substrate layer. A dielectric layer couples with the AC electrode layer. An aperture electrode layer couples with the dielectric layer and is electrically insulated by the dielectric layer from the AC electrode layer. Further, a heater couples with the substrate layer on an opposite side of the AC electrode layer.